JPH05152611A - Manufacture of led semiconductor chip for led array print head - Google Patents

Abstract

PURPOSE:To reduce the fraction defective at the time of manufacturing an LED semiconductor chip provided with a plurality of light emitting element sections by cutting a wafer along longitudinal and transversal parting lines drawn on the wafer. CONSTITUTION:After forming indentation grooves 7 along at least transversal parting lines parallel to both the left and right end faces of LED semiconductor chips 2 of the longitudinal parting lines Al and transversal parting lines which are drawn on a wafer A for dividing the wafer A into each chip 2, the wafer A is divided into the chips 2 by cutting the wafer A in the grooves 7.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an LED semiconductor chip having a light emitting element portion in an LED array print head used as a light source in an electrophotographic printer or the like.

[0002]

2. Description of the Related Art Generally, an LED array printhead of this type is described in JP-A-2-184466, and as shown in FIGS. 1 to 3, on an upper surface of a substrate 1,
A plurality of LED semiconductor chips 2 each having a length L in which a plurality of light emitting element portions 3 are formed in a line on the upper surface at a constant pitch P are arranged so that the light emitting element portions 3 in each LED semiconductor chip 2 are aligned. It is configured to be mounted side by side.

In each of the LED semiconductor chips 2
Reference numeral 4 denotes Ga for forming the light emitting element section 3.
-As-P type diffusion layer, reference numeral 5 is a diffusion barrier layer (insulation
Layer), reference numeral 6 is an electrode conductor connected to the light emitting element section 3.
Each is shown. Further, in manufacturing the LED semiconductor chip 2,
Then, conventionally, as shown in FIG.
The surface of this wafer A is made by using wafer A made by CON
Then, the Ga-As-P-based diffusion layer 4 is formed on the
Several vertical dividing lines A₁And a plurality of horizontal dividing lines A₂By
Diffusion burrs are placed on each partitioned LED semiconductor chip 2.
The layer 5, the light emitting element portion 3 and the electrode conductor 6 are formed respectively.
After that, the wafer A is replaced with a diamond grindstone B or a die.
With a cutting tool such as a sing saw, each vertical dividing line A ₁And each
Horizontal dividing line A₂Each LED by cutting along
The method of dividing each semiconductor chip 2 is adopted.
It

When the wafer A is cut along the vertical dividing lines A ₁ and the horizontal dividing lines A ₂ with the cutting tool such as the diamond grindstone B or the dicing saw as described above, the cutting portion Inevitably, microcracks and chipping occur, and peeling of the diffusion barrier layer 6 also occurs.

[0005]

By the way, the above-mentioned LED
In the array print head, when a plurality of LED semiconductor chips 2 are mounted in a line on the upper surface of the substrate 1, the pitch interval P in each light emitting element section 3 is set to L
In addition to having to have a constant pitch interval P also at the joint portion of the ED semiconductor chip 2, each LED
Since it is necessary to make a gap at the joint portion of the semiconductor chip 2, the light emitting element portion 3 adjacent to the left and right end surfaces 2a of the LED semiconductor chip 2 among the light emitting element portions 3 of each LED semiconductor chip 2 is The shape is such that it is located in a region extremely close to the left and right end faces 2a.

On the other hand, in the LED semiconductor chip 2
The left and right end surfaces 2a are formed by diamond-grinding the wafer A.
Each horizontal division with a cutting tool such as stone B or a dicing saw
Line A ₂Formed by cutting along
Therefore, each luminescent element in each LED semiconductor chip 2
Left and right end faces 2 of the LED semiconductor chip 2 of the child portion 3
The light-emitting element portion 3 adjacent to a has a sharp edge on both end faces 2a.
Wafer A
Micro cracks that are inevitably generated when cutting
It is affected by chipping and peeling of the diffusion barrier layer 6.
However, the brightness is lower than the brightness of other light emitting elements.
LED semiconductor chips are mounted on the wafer
If the production rate of defective products is high when using
There was a problem to say.

In particular, this problem, that is, the tendency of occurrence of defective rate is high, is that the narrower the pitch interval P of the light emitting element portions 3 is, that is, the number of the light emitting element portions 3 per unit length, that is, the dot. It increases in proportion to the number. SUMMARY OF THE INVENTION It is a technical object of the present invention to provide a manufacturing method capable of reliably reducing the incidence of defective products when manufacturing LED semiconductor chips using a wafer.

[0008]

In order to achieve this technical object, the present invention provides a diffusion layer on the surface of a wafer,
Then, after forming a diffusion barrier layer, a light emitting element section and an electrode conductor at the location of each LED semiconductor chip partitioned by a plurality of vertical division lines and a plurality of horizontal division lines,
In the method for manufacturing an LED semiconductor chip, the wafer is cut and divided for each LED semiconductor chip by cutting the wafer along each of the vertical dividing lines and each of the horizontal dividing lines with a cutting tool. A recessed groove is formed along each of the horizontal dividing lines at least in a portion of each of the vertical dividing lines and each of the horizontal dividing lines that are divided for each semiconductor chip, the horizontal dividing line being parallel to the left and right end surfaces of the LED semiconductor chip. Then, the wafer is cut and divided in the groove.

[0009]

[Operation] As described above, among the vertical dividing lines and the horizontal dividing lines that divide the wafer into the LED semiconductor chips, at least the horizontal dividing lines parallel to the left and right end surfaces of the LED semiconductor chip are recessed. Grooves are formed so as to extend along each of the horizontal dividing lines, and the wafer is cut / divided in the recessed grooves by cutting tools so that each LED semiconductor chip is cut / divided by a cutting tool. In this case, since damage to the diffusion layer and the diffusion barrier layer of the left and right end faces of each LED semiconductor chip can be reduced by the presence of the recessed groove, the left and right end faces of each LED semiconductor chip can be reduced. It is possible to significantly reduce the occurrence of microcracks, chipping and peeling in the diffusion layer and the diffusion barrier layer.

[0010]

Therefore, according to the present invention, when an LED semiconductor chip is manufactured using a wafer,
L of each light emitting element portion in the LED semiconductor chip
The occurrence rate of defective products in which the brightness of the adjacent light emitting element portions on the left and right end surfaces of the ED semiconductor chip decreases and the defective products are
It has an effect that can be surely reduced.

[0011]

Embodiments of the present invention will now be described with reference to the drawings (FIGS. 5 to 1).
3) will be described. In this figure, reference numeral A is a Ga-As type sircon made by dividing into a plurality of LED semiconductor chips 2 along a plurality of vertical dividing lines A ₁ and a plurality of horizontal dividing lines A ₂ . A wafer is shown, and on the upper surface of the wafer A, as shown in FIGS.
After the diffusion layer 4 of a-As-P type is formed, a diffusion barrier layer 5 having a plurality of cut-out windows 5a is formed on the upper surface of the diffusion layer 4 in the portion of each LED semiconductor chip 2.

[0012] Then, the a portion of the wafer each transverse dividing line of the top surface of A A _2, as shown in FIGS. 8 and 9, the recessed groove 7, extending along the each lateral division line A ₂ To form. As is well known in the art, each of the recessed grooves 7 is formed with a photoresist film on the upper surface of the wafer A, and the photoresist film is mask-exposed with a pattern having the same shape as the recessed grooves 7. After that, by developing, an opening having the same shape as that of the recessed groove 7 is formed. Then, after etching with an etching solution, the photoresist film is removed by a so-called photoetching method.

Next, as shown in FIGS. 10 and 11, by diffusing the upper surface of the wafer A, light is emitted to a portion of the diffusion layer 4 in each of the vent windows 5a in the diffusion barrier layer 5. Each of the element parts 3 is formed, and then
Electrode conductors 6 are formed on the respective light emitting element portions 3, and a back metal layer 8 is formed on the lower surface of the wafer A.

Then, the wafer A is shown in FIGS.
As shown in 13, diamond grinding stone B or dicing
Each vertical dividing line A with a cutting tool such as a saw₁And each horizontal division
Line A ₂Each LED semiconductor by cutting along
When dividing into chips 2, each of the horizontal dividing lines A₂
Cutting along the inside of each groove 7
To do.

Then, when the wafer A is cut and divided for each LED semiconductor chip 2 by a cutting tool such as a diamond grindstone B or a dicing saw, each LED is cut.
Since the damage to the diffusion layer 4 and the diffusion barrier layer 5 of the left and right end surfaces 2a of the semiconductor chip 2 can be reduced by the presence of the recessed groove 7, the left and right end surfaces 2a of each LED semiconductor chip 2 can be reduced. Out of diffusion layer 4
It is possible to significantly reduce the occurrence of microcracks, chipping and peeling in the diffusion barrier layer 5 and the diffusion barrier layer 5.

In this case, the depth of each of the recessed grooves 7 is preferably equal to the thickness of the light emitting element portion 3 formed in the diffusion layer 4 or larger than the thickness of the light emitting element portion 3. Further, the width dimension of each recessed groove 7 is preferably equal to or larger than the cutting width in the cutting tool such as the diamond grindstone B or the dicing saw.

Although the above-mentioned embodiment shows the case where the recessed groove 7 at each horizontal dividing line A ₂ is formed at the time after the diffusion barrier layer 5 is formed, the present invention is not limited to this. Instead, the recessed groove 7 may be formed after the light emitting element portion 3 is formed, or may be formed after the electrode conductor 6 is formed.

Further, in addition to forming the recessed groove at the position of each horizontal dividing line A ₂ as in the above-described embodiment, at the position of each vertical dividing line A ₁ , the vertical dividing line A ₁ is formed. It may be formed so as to extend along it.

[Brief description of drawings]

FIG. 1 is an enlarged perspective view showing a main part of an LED array printhead.

FIG. 2 is a sectional view taken along line II-II of FIG.

FIG. 3 is a sectional view taken along line III-III in FIG.

FIG. 4 is a perspective view showing a conventional manufacturing method.

FIG. 5 is a perspective view of a wafer used in the method of the present invention.

6 is an enlarged sectional view taken along line VI-VI of FIG.

FIG. 7 is an enlarged sectional view taken along line VII-VII of FIG.

8 is a perspective view showing a state in which a recessed groove is formed on the upper surface of the wafer in FIG.

9 is an enlarged sectional view taken along line IX-IX of FIG.

10 is an enlarged cross-sectional view of a state in which a light emitting element portion is formed on the wafer in FIG.

11 is a sectional view taken along line XI-XI of FIG.

12 is a perspective view showing a state in which the wafer of FIG. 5 is cut and divided into LED semiconductor chips.

13 is an enlarged sectional view taken along line XIII-XIII in FIG.

[Explanation of symbols]

A Wafer A ₁ Vertical dividing line A ₂ Horizontal dividing line B Diamond grindstone 2 LED semiconductor chip 2a Left and right end surfaces of LED semiconductor chip 3 Light emitting element section 4 Diffusion layer 5 Diffusion barrier layer 6 Electrode conductor 7 Recessed groove

Claims (1)

[Claims] 1. A diffusion layer is formed on the surface of a wafer, and then, a diffusion barrier layer and a light emitting element section are provided at the positions of each LED semiconductor chip partitioned by a plurality of vertical dividing lines and a plurality of horizontal dividing lines. After forming the electrode conductors and the electrode conductors respectively, the wafer is cut along the vertical dividing lines and the horizontal dividing lines with a cutting tool to cut and divide each LED semiconductor chip. In the method of manufacturing a chip, a recessed groove is formed in at least a portion of each vertical division line and each horizontal division line that is divided for each of the LED semiconductor chips, the horizontal division line being parallel to the left and right end surfaces of the LED semiconductor chip. In an LED array print head, which is formed so as to extend along each horizontal division line, and cuts and divides the wafer in the concave groove. Manufacturing method of ED semiconductor chip.